Since thienamycin having useful activities as an antibiotic was discovered, a number of carbapenem derivatives have been synthesized and applied for patents Prior art relevant to the present invention is found, for example, in U.S. Pat. Nos. 4,696,923 and 4,717,728. The carbapenem derivatives disclosed in U.S. Pat. No. 4,696,923 have a 3-azetidinylthio group, a 3-pyrrolidinylthio group, a 4-piperidylthio group, etc. whose N-atom is substituted with a substituted amidino group, a formimidoyl- group, etc. at the 2-position of the carbapenem skeleton However, these compounds are confined to those in which the heterocyclic moiety of the heterocyclic thio group is saturated and carries no substituent on its carbon atoms. On the other hand, U.S. Pat. No. 4,717,728 discloses carbapenem compounds having a cyclic amidinylthio group at the 2-position of the carbapenem skeleton. The cyclic amidinyl group or cyclic guanidinyl group of these compounds has no substituent on the ring-forming carbon atoms and is limited to a 2-imino-1-(substituted or unsubstituted)piperidin-3-ylthio group.
Besides, both the above-described relevant references give no specific antimicrobial spectral data of their typical compounds.
While carbapenem derivatives are useful for the treatment of human and animal diseases caused by pathogenic bacteria, antibacterial activities of the state-of-the-art carbapenem derivatives are not sufficiently satisfactory, and there has been a demand to develop a compound exhibiting excellent antibacterial activities against various pathogenic bacteria.
Imipenem, a carbapenem compound now clinically used, is decomposed by renal dehydropeptidase (hereinafter abbreviated as DHP) similarly to thienamycin, so that it is used in combination with a DHP inhibitor, e.g., cilastatin. Hence, a carbapenem compound having improved stability against DHP as well as satisfactory antibacterial activity has been demanded.